1. Field of the Invention
This invention relates to a signal reproducing apparatus, and more particularly to a signal reproducing apparatus arranged to be capable of performing tracking control in reproducing signals from a recording medium on which tracks are formed.
2. Description of the Related Art
Reproduction tracking control methods which have heretofore been put in practice for home VTRs include methods called a CTL method and a 4f ATF method. According to the CTL method, a fixed magnetic head is disposed at a part of a tape path separately from a rotary head. The fixed magnetic head is arranged to record, as a CTL signal, a vertical synchronizing signal separated from a video signal in a control track provided in the longitudinal direction of a tape. At the time of reproduction, the CTL signal is reproduced and used for tracking. In the case of the 4f ATF method, a rotary head which is arranged to record and reproduce a main signal including a video signal and an audio signal is used to record pilot signals of four different relatively-low frequencies by superimposing them on the main signal in rotation in a circulating manner, and, at the time of reproduction, a tracking error signal (ATF error signal) is obtained by comparing with each other crosstalk components of the pilot signals reproduced from two tracks adjoining the track which is being subjected to reproduction.
Home VTRs have recently come to be arranged to give high quality images and to operate in a digital manner. As a result, for recording and reproducing a relatively large amount of information, some of digital VTRs have been arranged to divide an image signal for one frame and to record the divided image signals in a plurality of tracks. Studies are now conducted for various tracking methods applicable to the digital VTRs of that kind.
With respect to reproduction tracking control, in cases where tape path adjustment, tag recording, after-recording, insert recording, etc., are to be made, it has been practiced to make a so-called tracking shift by intentionally shifting the phase of the rotary head relative to tracks.
There has been proposed a 2f ATF method which differs from the above-stated 4f ATF method. According to the 2f ATF method, pilot signals are recorded in every other track. More specifically, a pilot signal of a frequency f1 and a pilot signal of a frequency f2 are alternately recorded in every other track. Hence, no pilot signal is recorded in every other track on the tape.
In carrying out reproduction tracking control in accordance with the 2f ATF method, a tracking error signal is obtained only from the pilot signals of frequencies f1 and f2 recorded in two adjacent tracks reproduced by one of two rotary heads, i.e., a head of a first channel, which is reproducing tracks in which no pilot signal is recorded. The other rotary head, i.e., a head of a second channel, on the other hand, has no pilot signal reproduced in two adjacent tracks and reproduces tracks having the pilot signals recorded.
With respect to the above-stated tracking shift, the CTL method is very easily carried out. In other words, the tracking control is performed on the basis of a phase difference between a CTL signal reproduced and a rotary-head rotation phase detection signal. Therefore, the tracking shift can be carried out as desired by switching the delay time of either the CTL signal or the rotary-head rotation phase detection signal. In the case of the above-stated method of using the pilot signals, on the other hand, the concept of carrying out a simple tracking shift such as the one used by the CTL method has not been taken into consideration.